1. Consider an atom traveling at 2% of the speed of light. The de Broglie wavelength is found to be 3.50 × 10–6 nm. Which element is this? (Planck’s constant, h = 6.626 × 10-34 J⋅s)
(A) O (16.00) (B) F (19.00) (C) S (32.06) (D) Ar (39.95)
2. The autoionization of water, H2O(l) + H2O(l) H3O+ (aq) + OH– (aq), is known to be endothermic. Which of the following correctly states what occurs as the temperature of water is raised?
(A) The pH of the water does not change, and the water remains neutral.
(B) The pH of the water decreases, and the water becomes more acidic.
(C) The pH of the water increases and the water remains neutral.
(D) The pH of the water decreases, and the water remains neutral.
3. Which of the following result(s) in an increase in the entropy of the system? I.Br2(g) → Br2(l), II. NaBr(s) →Na+ (aq) + Br– (aq), III. O2(298 K) → O2(373 K), IV. NH3(1 atm, 298 K) → NH3(3 atm, 298 K)
(A) I, III (B) II, III (C) I, II, III (D) II, III, IV
4. For the reaction A + B C + D, ∆H° = +40 kJ and ∆S° = +50 J/K. Therefore, the reaction under standard conditions is
(A) spontaneous at temperatures less than 10 K
(B) spontaneous at temperatures greater than 800 K
(C) spontaneous only at temperatures between 10 K and 800 K
(D) spontaneous at all temperatures